The first Germanic peoples to cross into Roman territories did
so to carry out raids and loot. They then returned to their
homelands. The First Germanic peoples to settle in parts of the
Roman Empire were the Salian Franks and the Visigoths.
The Salian Franks moved across the mouth of the River Rhine into
Holland south of that river and northern Belgium in the late 3rd
century. They did so because they were pushed southwards by other
Germanic peoples, probably the Saxons. The Romans allowed them to
settle in this area, which they called Toxandria, and gave them
protection. The Salian Franks became allies of the Romans, and
fought alongside their troops and supplied solders for the Roman
army.
The Visigoths asked the Romans to allow them to settle in the
lower Danube area of the Roman Empire to escape the advance of the
Huns into eastern Europe. The emperor Valens granted this in
376.